It is Blanchett's second appearance and the first for Nyong'o on the annual list, which does not rank its fashion stars. The style setters list is dominated by actors, but it also includes European royals, sports stars and artists.
Princess Mary of Denmark, Queen Maxima of the Netherlands and "Downton Abbey" actress Michelle Dockery were noted for their style, along with artist Jeff Koons, New York Giant football wide receiver Victor Cruz and Grammy-winning musician Pharrell Williams.
Williams, on the list for a second time, named actor Johnny Depp as his style icon, while Cruz said he admired Williams for his style.
Although Nyong'o has been praised for her fashion flair, when asked to name her favorite places to shop she told the magazine, "nowhere. I dislike shopping."
Tony award winner Neil Patrick Harris was another first-timer on the list, along with actors Benedict Cumberbatch, Idris Elba, Emmy Rossum and "Harry Potter" star Emma Watson, who said her favorite place to shop was British retail chain Topshop.
The Duchess of Cambridge, a fixture of the list for four years, will be joined in the magazine's best-dressed Hall of Fame by German fashion designer Karl Lagerfeld, the creative force behind Chanel.
The full list will be published in the September issue of the magazine, which goes on sale on Aug. 12.